Remote control system



Ap il 1957 w. SMOOT EAL 2,788,517

REMOTE CONTROL SYSTEM Filed Dec. 30, 1954 AAAA A'AIA'A g 40 so Unit 3 T6 Other Control Units WITNESSES INVENTQRS Warren L Smoot 8 W ML Weldon R. Donsbuch. YFM

ATTORNEY United States Patent REMOTE CONTROL SYSTEM WarrenL. Smoot, Pikesville, and Weldon R. Donsbach, -Baltimore, Md., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania 2 Application December 30, 1954, Serial No. 478,604 11 Claims. Cl. 340-226) This invention relates to electrical control systems and more particularly. to a control system in which a plurality of remote control stations are used for remotely switching electrical utilization apparatus.

One of the objects of our invention is to provide a simplified remote control'systein' employing a limited number of components. When a considerable distance separates electrical utilization apparatus and a remote station for controlling that apparatus, it is desirable to use the least number of conductors between the two locations. This is especially true where a number of remote stations are used to control the same apparatus. Accordingly, we have provided a system in which many remote control stations are connected to electrical utilization apparatus through a minimum number of conductors.

Another object of our invention is to provide a control system employing a plurality of remote control stations which indicate to each other the condition of the controlled apparatus effected by any one of the stations in the system.

In the embodiment of the invention hereinafter described, two relays can be controlled by first, second and third push-button switches located at each remote control station in the system. Closure of the first switch at one station will have the same effect as closure of the corresponding first switch at any other station. In a similar manner, closure of the second switch at a particular station will have the same eifect as closure of any other second switch, and so on. When the first pushbutton switch at any station is depressed, it will cause a first indicating lamp to light at each remote control station in the system. Likewise, when the second or third switch is depressed at any station, second or third lamps at each remote control station will light, thereby indicating to all stations the push-button last depressed by an operator at one of the stations. The system is further characterized by an automatic extinguishment of all other lamps where one set of lamps are lighted in response to, say, depression of one of the first pushbutton switches.

Other objects and features of our invention will become apparent from the following detailed description taken in connection with the accompanying single figure drawing, which illustrates the invention schematically.

Referring to the drawing, the circuit shown includes a pair of relays and 12 equipped with energizing coils 14 and 16, respectively. In the present embodiment of the invention, relays 10 and 12 are each provided with two normally open contacts; however, the number of contacts may obviously be increased if desired. When contact 18 of relay 10 is closed, a holding circuit is efiected for the relay through contact 18, resistor 20, a direct-current voltage source 22 which has its negative terminal grounded and ground. Likewise, closure of contact 24 will effect a holding circuit for relay 12 through resistor 26, voltage source 22, and

2,788,517 Patented Apr. 9, 1957 ice ground. Contacts 28 and 30 are available for external circuitry, not shown, which may be used to perform various desired functions.

. In order to control operation of relays 10 and 12, a plurality of remote control units are provided. These units are connected to the relays in parallel through two conductors 32 and 34. Since the units are substantialiy identical in construction, only one will be described in detail. Referring to unit No. 1, a source of directcurrent voltage 36 is provided for initially closing contacts 18 and 24 to effect the aforesaid holding circuits for relays 1t and 12. The operation of the relays is controlled by three self-restoring, momentary contact push-button switches 38, 40, and 42. Assuming that the relays are in the position shown in the drawing and that switch 38 is momentarily closed, relay 10 will be energized through conductor 32, contact 44 of switch 38, voltage source 36, and ground. Once relay 10 is energized upon the momentary closure of switch 38, contact 18 will close and a holding circuit for the relay 10 will be effected through voltage source 22. It should be noted that the closure of switch 38 also grounds conductor 34 at point .48 through contact 46. Therefore, if relay 12 should be energized immediately preceding the momentary closure of switch 38, it will become deenergized since both of its terminals are now grounded, one at point 50 and the other at point 48. Once the relay 12 is deenergized and its contact 24 opens, its holding circuit is broken. An external voltage source 36 must be applied to relay 12 to again effect a holding circuit therefor.

If switch 42 should be depressed momentarily, the process described above will be reversed. That is, relay 12 will be energized through conductor 34, contact 52, voltage source 36 and ground; whereas relay 10 will be deenergized since both of its terminals are grounded, one at point 56 and the other through contact 54 at point 48.

If switch 40 should be momentarily closed, either or both of the relays 10 and 12 will become deenergized.

since conductors 32 and 34 are then grounded atv point 48 via contacts 56 and 58.

control unit in the system. When both relays are deenergized, lamp 60 will light, being supplied with electrical energy from voltage source 66. The direction of current flow for lamp 60, in the conventional sense, will be from the positive terminal of source 66, through ground, coils 14 and 16, conductors 32 and 34, resistors 68 and 70, and resistor 72. Lamps 62 and 64 do not light at this time because the resistance of coils 14' and 16 is relatively low as compared to the resistance offered by resistors 74 and 76 and because the voltage developed across these resistors is not sufficient to cause lamps 62 and 64 to light.

If switch 38 should now be closed, the direction of conventional current flow in conductor 32 will be reversed and the voltage across lamp 60 from source 66 will be cancelled. Lamp 60 will, therefore, extinguish. However, lamp 62 will now light, being supplied with electrical energy from voltage source 36. After the switch 42 is momentarily closed, conductor 32 will be grounded thereby deenergizing relay 10 and causing lamp 62 to extinguish. At the same line, relay 12 will be energized and lamp 64 will light. If switch 40 is closed,

both of conductors 32 and 34 will be grounded, thereby 3 causing lamp to again light while extinguishing lamps 62 and 64.

It is important to note that the corresponding elements in the various control units are all connected in parallel between, ground and one or the other of conductors 32' and 34, For example; the paths defined when contacts 44 of switches 38 in units 1 and 2 close are in parallel. Likewise, the paths defined when contacts 52 or 56 close are also in parallel, and so on. It becomes evident, therefore, that closure or" a switch in one unit will have the same elfect as closure of its corresponding switch in any of the other control units. In a similar manner, the lamps 62 in'the various 'units are all connected in parallel between ground and conductor 32, lamps 64 are in. parallel between ground and conductor 34; and lamps 60 are in parallel between ground and both of conductors 32 and 34. In this manner, all of the parallelcon'nected lamps in the units will light simultaneously so that an operator at any unit in the system will be apprised of the push button last depressed at another station and, consequently, the condition of relays and Although the voltage sources 36 and 66 have been shown herein as separate for each control unit, it should be readily apparent that a single voltage source for all of the units may be used in their place. In actual practice, however, it is usually preferable to use separate voltage sources as shown since the control units will be separated by considerable distances.

We have described our invention in connection with a certain specific embodiment. It should be readily apparent, however, that various changes in form and arrangement of parts can be made to suit requirements without departing from the spirit and scope of the invention. In this respect, it is apparent that the number of parallel-connected control units can be extended to any desired number.

We claim as our invention:

1. In combination, a pair of relays, a first source of direct-current energy for said relays having its negative terminal grounded, a connection between one terminal of each of said relays and ground, a normally open contact for each of said relays effective when closed' to connect the other terminal of its associated relay to the positive terminal of said first energy source, a second source of direct-current energy for initially energizing each of said relays to efiect. a holding circuit therefor through said normally open contact and said first energy source, a connection between the negative terminal of said second energy source and ground, first and second conductors each of which is connected to the said other terminal of one or the other of said relays, a first switching device adapted when closed to connect the first of said conductors to the positive terminal of said second directcurrent energy source and the second of said conductors to ground, a second switching device adapted when closed to connect the first of said conductors to ground and the second of said conductors to the positive terminal of said second direct-current energy source, a third switching device adapted when closed to ground each of said conductors, a first indicating device connected between the first of said conductors and ground for indicating an energized condition of one of said relays, a second indicating device connected between the second of said conductors and ground for indicating an energized condition of the other of said relays, a two-terminal third indicating device and a source of direct-current potential for said third device having its positive terminal grounded, a connection between one of the terminals of said third indicating device and each of said first and second conductors, and a connection between the other terminal of said third indicating device and the negative terminal of said source of direct-current potential for said third device. r 7

2 The combination claimed in claim 1 wherein the 4 first, second and third switching devices comprise selfrestoring momentary contact push-button switches.

3. The combination claimed in claim 1 and including first, second and third groups of switches connected to said conductors in parallel with said first, second and third switching devices respectively whereby closure of any one of the parallel-connected switches in each group will produce the same efiect as closure of its associated switching device.

4. The combination claimed in claim 1 and including a first plurality of indicating devices connected in parallel with said first indicating device between said first conductor and ground whereby each of said first plurality of indicating devices will simultaneously indicate an energized condition of said one relay, a second plurality of indicating devices connected in parallel with said second indicating device between said second conductor and ground whereby each of said second plurality of indicating devices will simultaneously indicate an energized condition of said other relay, and a third plurality of'indicating devices connected in parallel with said third indicating device whereby each of said third plurality of indicating devices will simultaneously indicate with said third indicating device.

5. In combination, first and second relays, a holding circuit for each of said relays, a single pair of normally open contacts for each of said relays effective when closed to complete said holding circuit, a source of directcurrent energy for initially energizing said relays to close said contacts and complete said holding circuits, and circuit means for controlling said relays and including a first switching device having a first pair of normally open contacts which are adapted when closed to apply said direct-current energy source to said first relay in a manner to energize the same, said first switching device also having a second pair of normally open contacts efiective when closed to cause deenergization of said second relay, a second switching device having a first pair of normally open contacts which are adapted when closed to apply said direct-current energy source to said second relay to energize the same, said second switching device also having a second pair of normally open contacts which are effective when closed to cause deenergization of said first relay, and a third switching device effective when closed to cause deenergization of both of said first and second relays.

6. The combination claimed in claim 5 and including a first device for indicating an energized condition of said first relay, a second device for indicating an energized condition of said second relay, and a third device for indicating a deenergized condition of said first and second relays.

7. In combination, first and second relays, a holding circuit for each of said relays, a normally open contact for each of said relays efiective when closed to complete said holding circuit, a source of direct-current energy for initially energizing said relays to close said contacts and complete said holding circuits, a first plu rality of switching devices any one of which is adapted when closed to apply said direct-current energy source to said first relay in a manner to energize the same, each of'said first switching devices also being effective when closed to cause deenergization of said second relay, a second plurality of switching devices any one of which is adapted when closed to apply said direct-current energy source to said second relay to energize the same, each of said second switching devices also being efiective when closed to cause deenergization of said' first relay, a third plurality of switching devices any one of which is eltective when closed to cause deenergization of both' of said first and second relays, and a single pair of conductors interconnecting said first, second and third pluralities of switches with said relays. i

8. The combination claimed in claim 7 and including a first plurality of indicating devices each of which is associated with one of said first plurality of switching devices, and means for efiecting actuation of each of said first plurality of indicating devices when any one of said first plurality of switching devices is closed; a second plurality of indicating devices each of which is associated with one of said second plurality of switching devices, and means for effecting actuation of each of said second plurality of indicating devices when any one of said second plurality of switching devices is closed; and a third plurality of indicating devices each of which is associated with one of said third plurality of switching devices, and means for effecting actuation of each of said third plurality of indicating devices when any one of said third plurality of switching devices is closed.

9. Circuit means comprising, in combination, a pair of relays, a holding circuit for each of said relays, a normally open contact for each of said relays effective when closed to complete said holding circuit, a single pair of conductors and a plurality of remote control stations connected to said relays through said conductors, each of said stations including first, second and third switching devices, each of said first switching devices being effective when closed to cause energization of one of said relays and deenergization of the other, each of said second switching devices being eifective when closed to cause energization of said other relay and deenergization of the said one relay, and each of said third switches being eifective when closed to cause deenergization of both of said relays.

10. The combination claimed in claim 9 and including a first plurality of indicating devices each of which is associated with one of said first switching devices at its particular remote control station, a second plurality of indicating devices each of which is associated with one of said second switching devices at its particular remote control station, a third plurality of indicating devices each of which is associated with one of said third switching devices at its particular remote control station, and means for actuating each indicating device in a plurality of indicating devices when any one of the switches associated with an indicating device in the plurality is closed.

11. In combination, first and second relays, a source of direct-current energy, means connecting one terminal of each of said relays to the negative terminal of said energy source, a first switching device adapted when closed to connect the other terminal of said first and second relays to the positive and negative terminals respectively of said energy source, a second switching device adapted when closed to connect the other terminal of said first and second relays to the negative and positive terminals respectively of said energy source, and a third switching device adapted when closed to connect the other terminal of each of said relays to the negative terminal of said energy source.

References Cited in the file of this patent UNITED STATES PATENTS 1,575,599 Hornberger Mar. 2, 1926 1,744,220 Gardner Jan. 21, 1930 1,765,538 Nelson June 24, 1930 2,527,280 Smith Oct. 24, 1950 2,629,863 Stern, et al. Feb. 24, 1953 

